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Thread: Fill flash in AV mode

  1. #1

    Default Fill flash in AV mode

    Dear all,

    need advice on using my 350D's flash as a fill flash. When using the flash in bright daylight at wide aperture, f2 example, in AV mode, the metering will warn me that my shots will be overexposed due to the flash.

    the only solution i know is to stop down the aperture untill i get a well exposed shot. Anyway to get around it? Is there anyway to get a wide aperture shot in bright day light, use the flash, and still would not get a overexposed shot?

    Appreciate all your comments

  2. #2
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    Default Re: Fill flash in AV mode

    Hmm...i think can try increasing the shutter speed or using a lower ISO speed?

  3. #3

    Default Re: Fill flash in AV mode

    Already at lowest ISO and the fastest shutter speed the cam can go is 1/200 because of the flash sync speed

  4. #4
    Moderator catchlights's Avatar
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    Default Re: Fill flash in AV mode

    Quote Originally Posted by CasonLyn
    Dear all,

    need advice on using my 350D's flash as a fill flash. When using the flash in bright daylight at wide aperture, f2 example, in AV mode, the metering will warn me that my shots will be overexposed due to the flash.

    the only solution i know is to stop down the aperture untill i get a well exposed shot. Anyway to get around it? Is there anyway to get a wide aperture shot in bright day light, use the flash, and still would not get a overexposed shot?

    Appreciate all your comments
    no,
    but can use ND filter on lens.

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    Default Re: Fill flash in AV mode

    I am not sure about Canon 350D. But with my D70s, I can reduce the build-in flash power.

    Maybe you can use manual flash, say 1/8 or 1/16 power???

    Regards,
    Arto.

  6. #6
    Moderator catchlights's Avatar
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    Default Re: Fill flash in AV mode

    Quote Originally Posted by Artosoft
    I am not sure about Canon 350D. But with my D70s, I can reduce the build-in flash power.

    Maybe you can use manual flash, say 1/8 or 1/16 power???

    Regards,
    Arto.
    the overexposed is due to the available light, not from the flash,
    let say under bright sun light, using ISO 100 the exposusre is f11, 1/250,
    if shoot at f2, 1/250, whith or without flash will still overexposed.

  7. #7

    Default Re: Fill flash in AV mode

    For example, I am taking portrait in AV mode in daylight. Set f2 and shutter is 1/1000 example. Then i realised there are shadows on subject face, so i pop up my flash and shoot again, aperture still at f2 but shutter now sync to 1/200.. thus the overexposure.

    from what i hear, the only way is to stop down aperture or get a speedlite with higher sync speed. thanks all

  8. #8
    Senior Member oracle0711's Avatar
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    Default Re: Fill flash in AV mode

    It will definitely be overexpose at f/2 and since the metering said so, push the aperture to a higher value... f/8 or f/11 and look at the exposure metering ....


    Quote Originally Posted by CasonLyn
    For example, I am taking portrait in AV mode in daylight. Set f2 and shutter is 1/1000 example. Then i realised there are shadows on subject face, so i pop up my flash and shoot again, aperture still at f2 but shutter now sync to 1/200.. thus the overexposure.

    from what i hear, the only way is to stop down aperture or get a speedlite with higher sync speed. thanks all

  9. #9
    Moderator catchlights's Avatar
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    Default Re: Fill flash in AV mode

    if I want to use big f-stop for outdoor portraits, my solution is shoot with available light only.
    if I really really need to use fill flash, have to live with shooting at f8 or f11.

    If you are using a high speed sync flash, most likely you are shooting with flash manual output.

    or else you can use a ND filter on lens.

  10. #10

    Default Re: Fill flash in AV mode

    Do you really need to use the flash to fill the shadows?

    You could use a reflector to fill the shadows if you are getting over exposed images shooting at f2.
    Or you could find some kind of diffusion/tranluscent material to put over your flash to cut down the intesity of the flash.

    That would be my suggestion and my $0.02

  11. #11
    Moderator catchlights's Avatar
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    Default Re: Fill flash in AV mode

    agreed hondasleeper,

    fill in flash has it limitation, same as using a reflector or shade the subject with tranluscent screen.

    so you have to assess the situation, and see what is the best solution.

  12. #12
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    Default Re: Fill flash in AV mode

    Quote Originally Posted by catchlights
    the overexposed is due to the available light, not from the flash,
    let say under bright sun light, using ISO 100 the exposusre is f11, 1/250,
    if shoot at f2, 1/250, whith or without flash will still overexposed.
    Ya... ya.... you are right... .

    I though it is overexposed by flash....

    ND filter (or polarizer) can be use. Or wait until almost rain, when the sun is not too strong... Or, shoot around 7-9am, or 5-6pm.

    Regards,
    Arto.
    Last edited by Artosoft; 4th May 2006 at 01:23 PM.

  13. #13
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    Default Re: Fill flash in AV mode

    Quote Originally Posted by CasonLyn
    Dear all,

    need advice on using my 350D's flash as a fill flash. When using the flash in bright daylight at wide aperture, f2 example, in AV mode, the metering will warn me that my shots will be overexposed due to the flash.

    the only solution i know is to stop down the aperture untill i get a well exposed shot. Anyway to get around it? Is there anyway to get a wide aperture shot in bright day light, use the flash, and still would not get a overexposed shot?

    Appreciate all your comments
    If without flash, your setting yields a properly exposed picture and flash for the same setting over exposes it, then maybe your flash was set to manual with a setting requiring a smaller aperture setting. Are you using the built in flash or external? If you were using the built in flash, then maybe you forgot to set it to auto or fill?

  14. #14
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    Default Re: Fill flash in AV mode

    I assume that your main objective is to use a large aperture like f/2 to obtain a blurred background and you are in bright sunlight? If so, you have 3 options to reduce shadows on your subjects:
    1. The first has been mentioned here already. Use ND filters or CirPols to cut down the amount of light.
    2. Use a reflector (also mentioned already), meaning no need for flash. But you'll need someone (or something) to hold the reflector for you.
    3. Get an external flash and use the FP Sync mode on the flash (hope I got the term correct).
    The reason why you cannot use the built-in flash in the situation you described is because your 350D's x-sync speed is 1/200. Whenever you pop-up the flash, the camera will automatically reduce the shutter speed to 1/200 or less (except for M-mode).

    With an external flash, you have the option of using the FP Sync mode to circumvent this 1/200 limit (note that not all flashes have this feature). However, in this mode the flash does not simply fire once. Instead, it pulses rapidly during the entire time that the shutter is opened. The downside to this is that the light produced is much less powerful - the effective range is much lesser.

    Hope this helps.

  15. #15

    Default Re: Fill flash in AV mode

    Canon calls it "High-Speed Sync". There is a switch on the flash unit to toggle between that and "Normal" sync. It allows you to fire the flash even when shutter speed is 1/2000s.

    Getting an external flash would be the best solution, and it would come in useful for many other situations as well.

    Otherwise a good workaround would be to use the camera's meter to get the Av settings, then switch to manual mode and use those settings. Not sure whether the built-in flash ETTL would work, though.

    Another way is to use flash exposure compensation (which you should anyway) to reduce the flash power to -2 stop. This gives you a much more natural fill-in for the shadow areas.

  16. #16

    Default Re: Fill flash in AV mode

    Thanks all for the advice, using SLR flash is kinda different from using my canon s45's, probably becos i was using P mode most of the time with S45, now using AV mode in 350D. Great learning experience

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